[PATCH] [30/275] USB: prevent buggy hubs from crashing the USB stack

[Andi Kleen]

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>

commit d199c96d41d80a567493e12b8e96ea056a1350c1 upstream.

If anyone comes across a high-speed hub that (by mistake or by design)
claims to have no Transaction Translators, plugging a full- or
low-speed device into it will cause the USB stack to crash.  This
patch (as1446) prevents the problem by ignoring such devices, since
the kernel has no way to communicate with them.

Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Tested-by: Perry Neben <neben@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/usb/core/hub.c |    5 +++++
 1 file changed, 5 insertions(+)

Index: linux-2.6.35.y/drivers/usb/core/hub.c
===================================================================
--- linux-2.6.35.y.orig/drivers/usb/core/hub.c	2011-03-29 22:51:56.618274449 -0700
+++ linux-2.6.35.y/drivers/usb/core/hub.c	2011-03-29 23:55:06.774293840 -0700
@@ -2721,6 +2721,11 @@
 		udev->ttport = hdev->ttport;
 	} else if (udev->speed != USB_SPEED_HIGH
 			&& hdev->speed == USB_SPEED_HIGH) {
+		if (!hub->tt.hub) {
+			dev_err(&udev->dev, "parent hub has no TT\n");
+			retval = -EINVAL;
+			goto fail;
+		}
 		udev->tt = &hub->tt;
 		udev->ttport = port1;
 	}
--
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